Publication: Optimal concentration of p-aminobenzoic acid and folic acid in the in vitro assay of antifolates against Plasmodium falciparum
Issued Date
1987-01-01
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ISSN
00029637
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2-s2.0-0023618362
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Mahidol University
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SCOPUS
Bibliographic Citation
American Journal of Tropical Medicine and Hygiene. Vol.37, No.1 (1987), 42-48
Suggested Citation
P. Tan-Ariya, C. R. Brockelman, C. Menabandhu Optimal concentration of p-aminobenzoic acid and folic acid in the in vitro assay of antifolates against Plasmodium falciparum. American Journal of Tropical Medicine and Hygiene. Vol.37, No.1 (1987), 42-48. doi:10.4269/ajtmh.1987.37.42 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/15353
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Title
Optimal concentration of p-aminobenzoic acid and folic acid in the in vitro assay of antifolates against Plasmodium falciparum
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Abstract
In vitro tests for Plasmodium falciparum sensitivity to pyrimethamine, sulfadoxine, and both drugs in combination were performed in four kinds of culture medium, each differing p-amino benzoic acid (PABA) and folic acid concentrations. Results of the tests using pyrimethamine-sensitive and pyrimethamine-resistant isolates indicated that drug activity was reduced proportionally to the concentrations of these two growth factors in the medium. The optimal concentrations of PABA and folic acid for parasite growth and drug susceptibility, as evaluated by microscopic examination and by the extent of incorporation of radioactive 14 C-pyrimethamine and 14 C-sulfadoxine, were 10 ng/ml and 2 ng/ml, respectively. Depletion of PABA and folic acid from the medium had no effect on drug-resistant parasites but multiplication of drug-sensitive isolates was markedly reduced. Medium containing 0.5 ng/ml PABA and 10 ng/ml folic acid was the best for parasite growth regardless of the degree of drug sensitivity. Results obtained by using this medium agreed most closely with results from in vivo observations.